Ray tracing in one weekend
This is a straightforward port of the code in Ray Tracing In One Weekend by Peter Shirley.
It's a wonderful book, and you can get it for $2.99 on amazon.
Source
This was captured (and branched) from revision 8de9020f09486897794be7db63383adc489df89b of the repository below by Nicholas Matsakis. The code is in the public domain.
